In going after tenure, Ms. Rhee is taking on the holiest citadel of the education establishment. This summer she offered a new teacher contract proposal with two options. Teachers could choose a plan under which their pay would rise spectacularly -- nearly doubling by 2010 -- in exchange for giving up tenure. Or they could opt for a smaller pay bump and still lose some seniority rights.

Ms. Rhee's proposal has caused a meltdown among leaders of the Washington Teachers' Union, and negotiations have collapsed. The Chancellor has raised the stakes, announcing the district would seek to dismiss tenured teachers who are ineffective. She has also hinted she'll go around the union by creating more nonunionized charter schools, or getting the federal government to deem her district in a "state of emergency."

Plucked from a nonprofit by D.C. Mayor Adrian Fenty, Ms. Rhee (a Democrat) has spent the past 18 months puncturing other education taboos. She closed 23 failing schools and restructured 27 more. She fired nearly one-third of the district's principals and reduced a bloated bureaucracy. She dismisses as "complete crap" the argument that students can't learn because of disadvantaged backgrounds.